soc: qcom: Add device tree binding for Shared Memory Device
authorBjorn Andersson <bjorn.andersson@sonymobile.com>
Tue, 28 Jul 2015 03:20:29 +0000 (20:20 -0700)
committerAndy Gross <agross@codeaurora.org>
Wed, 29 Jul 2015 19:13:48 +0000 (14:13 -0500)
Add device tree binding documentation for the Qualcomm Shared Memory
Device, used for communication between the various CPUs in the Qualcomm
SoCs.

Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Signed-off-by: Andy Gross <agross@codeaurora.org>
Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt [new file with mode: 0644]

diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,smd.txt
new file mode 100644 (file)
index 0000000..f65c76d
--- /dev/null
@@ -0,0 +1,79 @@
+Qualcomm Shared Memory Driver (SMD) binding
+
+This binding describes the Qualcomm Shared Memory Driver, a fifo based
+communication channel for sending data between the various subsystems in
+Qualcomm platforms.
+
+- compatible:
+       Usage: required
+       Value type: <stringlist>
+       Definition: must be "qcom,smd"
+
+= EDGES
+
+Each subnode of the SMD node represents a remote subsystem or a remote
+processor of some sort - or in SMD language an "edge". The name of the edges
+are not important.
+The edge is described by the following properties:
+
+- interrupts:
+       Usage: required
+       Value type: <prop-encoded-array>
+       Definition: should specify the IRQ used by the remote processor to
+                   signal this processor about communication related updates
+
+- qcom,ipc:
+       Usage: required
+       Value type: <prop-encoded-array>
+       Definition: three entries specifying the outgoing ipc bit used for
+                   signaling the remote processor:
+                   - phandle to a syscon node representing the apcs registers
+                   - u32 representing offset to the register within the syscon
+                   - u32 representing the ipc bit within the register
+
+- qcom,smd-edge:
+       Usage: required
+       Value type: <u32>
+       Definition: the identifier of the remote processor in the smd channel
+                   allocation table
+
+= SMD DEVICES
+
+In turn, subnodes of the "edges" represent devices tied to SMD channels on that
+"edge". The names of the devices are not important. The properties of these
+nodes are defined by the individual bindings for the SMD devices - but must
+contain the following property:
+
+- qcom,smd-channels:
+       Usage: required
+       Value type: <stringlist>
+       Definition: a list of channels tied to this device, used for matching
+                   the device to channels
+
+= EXAMPLE
+
+The following example represents a smd node, with one edge representing the
+"rpm" subsystem. For the "rpm" subsystem we have a device tied to the
+"rpm_request" channel.
+
+       apcs: syscon@f9011000 {
+               compatible = "syscon";
+               reg = <0xf9011000 0x1000>;
+       };
+
+       smd {
+               compatible = "qcom,smd";
+
+               rpm {
+                       interrupts = <0 168 1>;
+                       qcom,ipc = <&apcs 8 0>;
+                       qcom,smd-edge = <15>;
+
+                       rpm_requests {
+                               compatible = "qcom,rpm-msm8974";
+                               qcom,smd-channels = "rpm_requests";
+
+                               ...
+                       };
+               };
+       };